[plug] Mailman Delays

[Tim]

Hopefully after this email, I should have gotten the mailman
processing delay down.

Lesson. smtpd_recipient_restrictions runs for every recipient in the
email, so even tho lots of sites recommend throwing all the
restrictions in there,  any that could cause a delay will cause the
delay for each recipient, and so are better in
smtpd_client_restrictions where it should only cause the delay once.

Tim